Effects of aging on efficiency of task switching in a variant of the Trail Making Test.

The Trail Making Test [TMT, R. M. Reitan, (see record 1960-00397-001), 1992] is extensively used in research in neuropsychology and in aging, in part because it has been postulated to reflect executive processes, such as planning and switching. However, neurocognitive and individual-difference based analyses of this test are complicated because of different spatial arrangements of targets, the use of letters only in Version B, and potential order effects when Version A is administered prior to Version B. The present article examines a variant of a TMT (called the Connections Test) that attempts to remedy these deficiencies. A structural equation model suggested that there were no direct effects of age on either the nonalternating or alternating versions of the Connections Test (analogous to TMT Versions A and B, respectively); rather, all age-related effects were mediated through effects on perceptual speed. Moreover, although the nonalternating and alternating versions were strongly related to one another, only the latter had significant independent relations with measures of higher order cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of steam cooking on distribution of paralytic shellfish toxins in different tissue compartments of scallops Patinopecten yessoensis

This study investigated the effect of steam cooking on distribution of paralytic shellfish poisoning toxins (PSP-toxins) in scallops Patinopecten yessoensis. Toxins analysis by high-performance liquid chromatography showed that most of the PSP-toxins (>70%) were accumulated in viscera and adductor muscle of the raw scallops. Steam cooking induced significant loss (p < 0.05) of PSP-toxins from viscera (16%), adductor muscle (24%), gill and mantle (11%) while 32% of the toxins were retained inside viscera and adductor muscle. Overall, 51% of PSP-toxins leaked out from scallop tissues during steam cooking. However, there was no significant loss (p > 0.05) of PSP-toxins from gonad. Consumption of viscera was the most significant risk factor for causing PSP, while gonad and scallop soup were the second most significant. A rapid PSP test further verified detectable levels of PSP-toxins in all samples. However, possible interfering substance(s) in adductor muscles and gonads might potentially affect the results from this test.     

Nano-LC FTICR tandem mass spectrometry for top-down proteomics: routine baseline unit mass resolution of whole cell lysate proteins up to 72 kDa

Current high-throughput top-down proteomic platforms provide routine identification of proteins less than 25 kDa with 4-D separations. This short communication reports the application of technological developments over the past few years that improve protein identification and characterization for masses greater than 25 kDa. Advances in separation science have allowed increased numbers of proteins to be identified, especially by nanoliquid chromatography (nLC) prior to mass spectrometry (MS) analysis. Further, a goal of high-throughput top-down proteomics is to extend the mass range for routine nLC MS analysis up to 80 kDa because gene sequence analysis predicts that ~70% of the human proteome is transcribed to be less than 80 kDa. Normally, large proteins greater than 50 kDa are identified and characterized by top-down proteomics through fraction collection and direct infusion at relatively low throughput. Further, other MS-based techniques provide top-down protein characterization, however at low resolution for intact mass measurement. Here, we present analysis of standard (up to 78 kDa) and whole cell lysate proteins by Fourier transform ion cyclotron resonance mass spectrometry (nLC electrospray ionization (ESI) FTICR MS). The separation platform reduced the complexity of the protein matrix so that, at 14.5 T, proteins from whole cell lysate up to 72 kDa are baseline mass resolved on a nano-LC chromatographic time scale. Further, the results document routine identification of proteins at improved throughput based on accurate mass measurement (less than 10 ppm mass error) of precursor and fragment ions for proteins up to 50 kDa.     

Robust analysis of the yeast proteome under 50 kDa by molecular-mass-based fractionation and top-down mass spectrometry

As the process of top-down mass spectrometry continues to mature, we benchmark the next installment of an improving methodology that incorporates a tube-gel electrophoresis (TGE) device to separate intact proteins by molecular mass. Top-down proteomics is accomplished in a robust fashion to yield the identification of hundreds of unique proteins, many of which correspond to multiple protein forms. The TGE platform separates 0-50 kDa proteins extracted from the yeast proteome into 12 fractions prior to automated nanocapillary LC-MS/MS in technical triplicate. The process may be completed in less than 72 h. From this study, 530 unique proteins and 1103 distinct protein species were identified and characterized, thus representing the highest coverage to date of the Saccharomyces cerevisiae proteome using top-down proteomics. The work signifies a significant step in the maturation of proteomics based on direct measurement and fragmentation of intact proteins.     

A review of the current status of cultural and rapid detection of Vibrio parahaemolyticus

Vibrio parahaemolyticus is ubiquitous in estuarine environments and can be commonly found in seafood products. This bacterial pathogen continues to emerge as an important cause of foodborne illness, and several foodborne disease outbreaks caused by V. parahaemolyticus have been linked to the consumption of contaminated seafood, in particular those consumed raw such as oysters. In response to these outbreaks, especially during the 1990s, several cultural, immunological‐based and molecular detection methods have been developed, which allow for rapid detection and quantification of total and pathogenic V. parahaemolyticus. The development of molecular methodology has allowed for clinical and environmental isolates of V. parahaemolyticus to be subtyped, thus providing the framework for risk‐based strategies aimed at controlling foodborne outbreaks cause by this pathogen. It is important that the detection and typing methods strive to accomplish detection and differentiation of the pathogenic strains from environmental (non‐pathogenic) ones, as well as to detect the presence of the organism and not just the presence of V. parahaemolyticus produced toxins, which can also be produced by closely related species. This review covers the current status of detection and typing methodology for identification and characterisation of V. parahaemolyticus from seafood.     

A One‐Pot Route to Faceted FePt‐Fe3O4 Dumbbells: Probing Morphology–Catalytic Activity Effects in O2 Reduction Catalysis

The design and synthesis of faceted nanoparticles with a controlled composition is of enormous importance to modern catalyst engineering. Faceted FePt‐Fe₃O₄ dumbbell nanoparticles are prepared by a simple, one‐pot technique that avoids the need for expensive additives or preformed seeds. The faceted product consists of an FePt octopod and a cubic Fe₃O₄ lobe, of mean diameter 13.6 and 14.9 nm, respectively. The mass normalized activity for electrocatalytic oxygen reduction shows that this new structure types outperforms related catalysts in alkaline media. This work illustrates the power of morphology control and tailoring crystal facet abundance at the nanoparticle surface for enhancing catalytic performance.     

Characteristics of the combustion synthesis of TiC and Fe-TiC composites

The combustion synthesis of TiC, using the thermal explosion mode, was investigated by varying some of the process parameters including the reactant particle size, the pre-compaction pressure, and the heating rate. Based on these observations, a combustion model for the reaction was developed. When iron was added to titanium and carbon black powders, the ignition temperature was dictated by the eutectic temperature of the Fe-Ti system. Iron acted as a moderator for the reaction and led to a decrease in the combustion temperature.     

Effect of liquid addition on the bulk and flow properties of fine and coarse glass beads

The effect of water on the packing and flow properties of fine and coarse particles was experimentally investigated. Four different particle sizes of glass beads, from 5 to 275 μm, were studied with increasing water weight‐percentages. Using a FT4 Powder Rheometer, changes in bulk properties were collected as a function of water content and particle size. The results show that water content plays a significant role on the packing and flow of the particles. Small amounts of water created porous aggregates due to liquid bridging. Greater amounts of water resulted in the filling of the void‐spaces. This was indicated by an increase in basic flow energy, density, and pressure drop, with a decrease in porosity. A greater understanding of bulk properties of wetted material is useful to develop standard systems that can be used to examine the behavior of more complex situations, and implement changes to improve materials handling and processing. © 2015 American Institute of Chemical Engineers AIChE J, 62: 648–658, 2016     

就业中心与城市发展

理论和实证研究表明,工业的空间分布对城市经济与城市效率密切相关.就业与城市经济增长的关系表现在:(1)劳动生产率和要素的生产率一般与就业密度和城市规模成正比,这与大城市相对高的工资相一致;(2)工业行业的多样化也促进城市经济的发展;(3)工业就业集中有利于提高生产率,城市企业的数量,工业产量和专利的产生;(4)就业的空间集聚在很大程度上影响城市交通投资和成本.